What Is The Difference Between Wet And Dry Offset Printing? a question that Cheryl G. Harris has learned a lot about.
Dry offset printing, as opposed to wet offset printing, uses arid ink that sticks to the plastic’s surface without smearing or smudging.
In the packaging sector, spot color graphics are frequently copied using dehydrated offset printing on resin buckets, mugs, and other cylindrical or conical-shaped items.
Takeaways
- The main differences are in the inks used for wet and dry offset printing.
- Wet offset printing uses liquid inks that require time to dry.
- Meanwhile, dry offset printing utilizes inks that are already dried on the printing plate.
- This allows dry offset printing to have a faster production time versus wet offset since there is no drying time required.
- However, the liquid inks in wet offset give superior color quality because colors can be blended directly on the paper.
- Dry offset has more consistent color since the dried inks do not bleed or blend.
- Additionally, wet offset can risk print issues if the paper gets dirty from the wet inks during printing.
- Dry offset reduces this potential problem since the inks are already dried on the plate.
What Is The Difference Between Wet And Dry Offset Printing?
Wet offset is different from dehydrated offset in that the plate is wetted with an isopropyl alcohol and water solution in the former case, while silicone is employed to the spots where the dye is not supposed to stick in the latter.
Unlike flexography, which uses a relief-filled plate with the original image, gravure or rotogravure uses oily ink to delineate the printable portions while covering the remaining exterior with a material that repels dye.
The same idea underlies both systems: resistance between the material that coats the parts of the plate that won’t be copied and the oily part of the ink.
Wet offset
Wet offset is the classic and most common form of indirect planographic copying. The areas of the plate that will not be copied are hydrophilic, while the areas containing the design that has to be copied are hydrophobic.
Only the inked areas are transferred to the substrate since the oil-based dye does not mix with water and does not adhere to the damped exterior.
It in two varieties: Heat set web offset printing process, where the press has a thermal curing system built in to speed up the solvents in the dye’s evaporation and subsequent cooling that settles the pigments on the substrate, and cold set web printing process details, where the ink dries by evaporation and the paper’s absorption process.
Process of Damp Lithography
- Printing Plate Creation: The process begins with the creation of a copying plate, usually made of aluminum or polyester. The plate contains the picture or text to be copied, with the non-image areas chemically treated to repel dye.
- Ink Application and Transmit: The copying plate is dampened with water, which attaches to the non-image areas. Ink is employed to the plate, adhering only to the image areas due to their affinity for oil-based dye. The inked image is then transmitted to a gummed fabric cylinder.
- Transmit to Printing Surface: The gummed fabric cylinder then transmits the inked image onto the final copying exterior, whether it be paper, cardboard, metal, or resin.
| Pros | Cons |
| High Image Quality: Damp offset copying delivers sharp and high-resolution pictures, making it suitable for copying fine details and intricate designs. | Time taken for the dye: One of the drawbacks of damp offset copying is that the copied material requires dehydrating time before handling or further processing. |
| Versatility in Materials: It can copy on various substrates, including rough or uneven exteriors, enabling its application in different industries. | Dye and Water Balance: Maintaining the right balance between dye and water is crucial for achieving optimal copying results. |
| Cost-effectiveness: It is cost-effective for high-volume copying due to its ability to maintain quality and speed over large copy runs. |
Dry Offset Printing
It is a popular method of copying plastic pails and other cylindrical or conical-shaped objects. It is an adaptation of offset copying, a popular technique of obtaining precise color and fine detail in high-quality photographs.
A metal copying plate is first etched with the picture in dehydrated offset copying before being put onto a copying machine. The picture from the plate is transferred by the printing press onto a gummed fabric, which subsequently transmits the picture onto the resin container.
Arid offset copying, as opposed to damp offset copying, uses a dehydrated dye that sticks to the plastic’s exterior without smearing or smudging.
In the packaging sector, spot color graphics are frequently copied using dehydrated litho copying on plastic buckets, mugs, and other cylindrical or conical-shaped items. In addition, toys, auto parts, and other consumer goods are made with it.
Process of Arid Offset Printing
- Plate Creation and dye application: Similar to damp offset copying, a copying plate with raised pictures is created. However, in dehydrated offset, the plate is usually made of a softer material like rubber. Dye is employed to the raised areas of the plate.
- Transmit of Dye to Rubber Blanket: The inked plate comes into contact with a gummed fabric cylinder. As the platter rotates, the inked raised areas transfer the image onto the gummed fabric.
- Transmit to Substrate: The gummed fabric cylinder then transmits the inked picture from the plate onto the final substrate. This method allows copying on non-planar exteriors like cups, containers, and other three-dimensional objects.
| Pros | Cons |
| Suitability for Curved Exteriors: Dehydrated offset copying excels in copying on curved or irregular exteriors, making it highly suitable for various packaging materials and containers. | Limited Image Resolution: Dehydrated offset copying may have limitations in achieving very high picture resolutions compared to other copying techniques. |
| Speed and Efficiency: It offers faster production speeds compared to other copying techniques due to its indirect transmit process and ability to copy on different substrates simultaneously. | Surface Preparation: The exterior of the substrate needs to be prepared adequately to ensure proper dye adhesion and high quality. |
| Consistency in Quality: Dehydrated offset copying provides consistent and reliable copying quality, making it a preferred choice for high-volume production. |
Factors Influencing the Choice Between Wet & Dry Printing
The choice between damp and dehydrated offset copying is influenced by several factors. Damp offset copying is widely used for packaging industry products, such as boxes, while dehydrated offset copying is widely used for printing items like brochures, business cards, and catalogs.
The final product is also a key factor, with damp copying often used for items that require a smooth, slightly raised effect, such as metal platters and rolls of paper. On the other hand, dehydrated copying is often used for items that require a crisp, accurate picture, such as collector stamps and thick layers of inkjet.
The type of printer and the paper surface used also play a role, with damp copying utilizing a metal plate and a moistening step, while dehydrated copying uses a gum stamp and does not require moisture.
Ultimately, the choice between damp and dehydrated offset copying comes down to the specific requirements of the product being produced, as well as the desired medium and final effect.
Print volume and production scale
- Wet Offset Printing: Ideal for large print volumes due to its cost-effectiveness over extensive runs, despite slower production speeds.
- Dehydrated offset Printing: Suited for high-speed production lines and shorter copy runs due to its faster production capabilities.
Material and substrate requirements
- Damp Lithography: Versatile in copying on various flat platters and materials, making it suitable for a wide range of substrates.
- Dehydrated Offset copying: Specifically designed for copying on curved or non-planar exteriors like containers, cups, and packaging materials.
Desired print quality and resolution
- Damp Litho: Known for delivering high-resolution pictures, making it preferable for intricate designs and fine details.
- Dehydrated Offset Printing: This may have limitations in achieving very high resolutions, especially for extremely detailed designs compared to distinctions between litho and offset printing.
Cost considerations and budget constraints
- Damp Litho: Economical for high-volume copying due to its ability to maintain quality and speed over large copy runs.
- Arid Offset Printing: While efficient, the setup costs for dehydrated offset may be higher, but it can be cost-effective for shorter runs or specific substrate requirements.
Environmental impact and sustainability
- Damp Lithography: Typically uses more water and solvents in the printing process, potentially leading to environmental concerns.
- Arid Offset Printing: Generally considered more environmentally friendly due to reduced solvent usage and faster production, which can contribute to lower energy consumption.
Understanding these factors is crucial for businesses and industries in choosing between damp and dehydrated offset copying methods.
The decision often involves considering the specific needs of the copying project, such as volume, substrate type, quality requirements, budget, and environmental considerations, to ensure the most efficient and suitable copying solution is chosen.
Frequently Asked Questions
Conclusion
The main difference between damp and dehydrated copying lies in the way the dye is transmitted onto the copying exterior.
Damp offset copying uses an intermediary blanket cylinder to transmit the dye from the platter to the copying exterior, while dehydrated offset copying uses a silicone gum platter to transmit the dye.
Wet offset copying is commonly used for copying higher quality engraving items like banknotes and stamps, as well as for copying on non-porous exteriors like glass and metal.
Arid offset copying, on the other hand, is more commonly used printing on paper and cardboard, such as catalogues, brochures, issue of stamps, and packaging.
Both damp and dehydrated copyings are also known as intaglio printing and are specialized rotary copying techniques done by specialists that offer different textures and effects on the final copied sheet of paper used.
If you have inquiries or seek further insight into comprehending the fundamentals of offset printing or advantages of offset printing, please reach out to us at wlo-usa.org for assistance. We are delighted to assist you whenever you require our support.
